Rotary piston pumps



Jan. 10, 1961 G. WIGGERMANN 2,967,491

ROTARY PISTON PUMPS Filed Jan. 25, 1954 4 Sheets-Sheet 1 M6 WWW Jan. 10, 1961 G. WIGGERMANN 2,967,491

ROTARY PISTON PUMPS Filed Jan. 25, 1954 4 Sheets-Sheet 2 gang JQMM r I, r

Jan. 10, 1961 G. WIGGERMANN 2,957,491

ROTARY PISTON PUMPS Filed Jan. 25, 1954 4 Sheets-Sheet 3 W TVA 8;

Jan. 10, 1961 G. WIGGERMANN 2,967,491

ROTARY PISTON PUMPS Filed Jan. 25, 1954 4 Sheets-Sheet 4 IN VEN TOR.

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BY Jfrf/(af A ia/W United States Patent ROTARY PISTON PUMPS Georg Wiggermann, Spitzgartenweg 10, Kressbronn am Bodensee, Germany Filed Jan. 25, 1954, Ser. No. 405,953

Claims priority, application Germany Jan. 24, 1953 8 Claims. (Cl. 103-462) The present invention relates to pumps and more particularly to rotary piston pumps.

Known rotary piston pumps have several disadvantages. The structure for adjusting the known pumps so as to regulate the direction and rate of flow of the pumped fluid is exceedingly bulky so that the known pumps are .quite large. Furthermore, it is not possible to obtain very eflicient operation at all speeds of the known pumps because the rate of leakage of the fluid within the pump housing, between relatively movable parts of the pump, increases as the rate of flow of the pumped fluid increases. Furthermore, the known pumps of this type are extremely noisy in operation, and sometimes the parts of these pumps vibrate quite violently. Also, the forces exerted by the pumped fluid against the parts of the known pumps are very seldom balanced so that the parts of these known pumps are almost always subjected to bending moments. Moreover, extremely complicated mechanisms are used in the known pumps to interconnect each piston rod with a piston and with the rotary head. A further disadvantage of the known pumps is that the fluid pressure of the pumped fluid presses movable parts of the pump toward stationary or other movable parts of the pump so that great friction results between these parts and adjustments are very difficult to carry out, particularly during operation of the pump.

One of the objects of the present invention is to overcome the above drawbacks by providing a pump adjusting structure which is smaller and more compact than known adjusting structures so that the entire size of the pump may be greatly reduced without reducing the capacity or efficiency of the pump.

Another object of the present invention is to provide a rotary piston pump which will operate at high efiiciency over a wide range of pump adjustments.

A further object of the present invention is to provide a rotary piston pump with an arrangement which greatly cuts down the leakage of the pumped fluid in the interior of the pump .between relatively sliding parts thereof, as compared to known pumps of this type.

An additional object of the present invention is to provide a pump capable of accomplishing the above objects and at the same time being substantially free of any unbalanced forces which create bending moments on the pump parts.

Still another object of the present invention is to provide a rotary piston pump which is extremely quiet while operating.

.A still further object of the present invention is to provide a minimum of friction between relatively sliding parts of the pump so that such parts may be easily adjusted with respect to each other.

Yet another object of the present invention is to provide an extremely simple means for connecting the pistons of the pump to the rotary head.

Also, it is an object of the present invention to pro vide for the rotatable rotary head of the pump a mouning which efficiently absorbs the axial thrust of the grotary head and which prevents axial shifting thereof Further, it is an object of the present invention to provide a flow path for the pumped fluid which has?! large cross section and a minimum number of changes in direction. I

In addition, the objectsof the present invention include the provision of a pump apparatus capable of accomplishing all of the above objects and, at the same time being made up of simple and ruggedly constructed parts which are fairly inexpensive to manufacture and which will give reliable service over a long period of time.

With the above objects in view, the present invention mainly consists of a rotary piston pump which includes a hollow housing having a cover provided at its inner race with a curved concave surface forming part of a cylinder, 7

this cover being formed with inlet and outlet openings extending from the curved surface of the cover through the same. A rotary head is rotatably mounted in the housing and is spaced from the cover. A plurality of piston rods are connected to the rotary headfor'ti-lting movement in all directions with respect to the same, these piston rods extending from the rotary head toward the housing cover and being distributed about the axis of rotation of the rotary head. A plurality of pistons are respectively connected to the piston rods at portions thereofspaced from the rotary head, and a cylinder drum is formed with a plurality of cylinder bores into which the pistons slidably extend, respectively, so that the cylinder drum and rotary head rotate together and so that the pistons reciprocate in the cylinder bores during rotation. of the cylinder drum and rotary head when the axes of rotation of the cylinder drum and rotaryheadare out coincidence with each other, the cylinder drum being formed with first passages respectively extending from the cylinder bores to the end face of the cylinder drum distant from the rotary head. A slide member whichis substantially smaller than the housing cover of the pump has a first convex face of the same curvature as the concave surface of the cover located in slidable engagement with this concave surface. The slide member has a second face opposite to its first face and located iii slidable engagement with the above-mentioned end face of the cylinder drum, the slide member covering the ends of the first passages at the said end face of the drum and 7 being formed with a pair of passages which respectively communicate at the first face of the-slidemember with j the inlet and outlet openings of the cover and which respectively terminate at' the second face of the slide meinher on opposite sides of the axis of rotation of the cylina der drum and along the path through which the outer ends of the first passages move during rotation of thefcylinder drum so that these first passages successively c'omjmunicate with the second pasages during rotation of'the drum. Finally, an adjusting means is operatively connected to the slide member for adjusting the position thereof along the concave surface of the cover so as tje thereby adjust the angle between the axes of rotation'o f the cylinder drum and rotary head.

The novel features which are considered as character istic for the invention are set forth in particular in th appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will"be best understood from the following description .of specific embodiments when read in connection with the acco'm panying drawings, in which:

Fig. l is a sectional, elevational view ofa pump constructed in accordance with the present invention, the section of Fig. 1 being taken along a central plane ofJthe 7 pump of the invention;

Fig. 2 is an elevational view of one half of the housing cover of the pump, as seen from the interior of the pump;

Fig. 3 is a sectional elevational view of a slide member for adjusting the pump, the section of Fig. 3 being taken through a groove of this slide member;

Fig. 4 shows one half of the slide member of Fig. 3 as seen from the cover of the pump housing, and Fig. 4 also shows the end face of the cylinder drum which slidably engages this slide member;

Fig. 5 is a side, elevational view of the slide member of the invention;

Fig. 6 is a sectional plan view through the cover of the pump housing, the slide member associated therewith, and structure for adjusting the slide member with respect to the housing cover;

Fig. 7 is a fragmentary view of an apertured plate used in the pump of the invention;

Fig. 8 is a partly sectional illustration of a piston rod :used in the pump of the invention and the structure for connecting this piston rod to a piston, on the one hand, and to the rotary head, on the other hand; and

Figs. 9 and 10 are respectively different perspective illustrations of a slide member forming part of the pump of the invention.

Referring now to the drawings and more particularly to Fig. 1, it will be seen that the rotary head 4 is rotatably mounted in the housing 1 of the pump through the medium of the roller bearing 3 whose outer race ring is located between a shoulder of the housing and a snap ring .2 located in an annular groove formed in the interior of the housing. The rollers of the roller bearing 3 engage the outer periphery of the rotary head 4, and the rotary head is provided with an annular flange 8 engaging a side face portion of the rollers of the bearing 3. The right face of the rotary head 4, as viewed in Fig. 1, bears against a plurality of hardened ball members 6 which are respectively freely located in the apertures of an apertured plate 7 (Figs. 1 and 7), this plate 7 being located between the rotary head 4 and a hardened plate 5 which is fixed in the interior of the pump housing 1. The apertured plate 7 rotates during rotation of the rotary head, and the ball members 6 serve to transfer the axial thrust of the rotary head to the housing. The cooperation between the fiange 8 of the rotary head and the rollers of the bearing 3 maintains the rotary head in engagement with the ball members 6. In order that it may be driven, the rotary head 4 is formed with a central opening having splines 9 which matingly cooperate with the splined end of an unillustrated drive shaft, the latter extending through the opening 10 formed in the right wall of the pump housing 1, as viewed in Fig. 1 and through the ring .11 which is fixed to the plate 5 and which serves to prevent dirt and other foreign matter from entering into the pump housing.

The pump housing is provided with a cover 12 which is formed in its interior with a recess 13 in the form of a segment of a right cylinder, the slide member 14 being located in this recess 13 of the cover 12. The slide member 14 has an elongated bearing pin 15 fixed thereto, and the cylinder drum 17 is provided with an axial bore into which the pin 15 slidably extends so that the cylinder drum 17 is in this way rotatably carried by the slide member 14, the cylinder drum 17 being formed with a plurality of cylinder bores 16 distributed about the axis of the cylinder drum. Pistons 18 are respectively located in a close sliding fit in the cylinder bores 16. A piston rod 19 is threadedly fixed to each of the pistons 18, each piston rod 19 having its end distant from piston 18 located in the interior of a rotary head recess 20 which forms a part of a sphere, and the several pistons being connected to the rotary head for tilting movement in all directions with respect to the same and terminating in the recesses 20 which are distributed about the axis of rotation of the rotary head. The recesses 20 are formed in part by a plate 22 which forms a part of the rotary head and which is fixed to the other plate of the rotary head 4 through the medium of the screws 21. The plate 22 is formed with cutouts 23 respectively.,communicating with the recesses 20 and through which the piston rods 19 respectively extend.

The slide member 14 has a pin 24 fixed thereto along the axis of bearing pin 15, this pin 24 having an outer spherical end which extends into a transverse recess 25 formed in an adjusting rod 27 which extends slidably into a bore 26 of the cover 12, the latter being further formed with an elongated slot 28 communicating with bore 26 and recess 13 and through which the pin 24 extends. Bore 26 and slot 28 are located in a plane normal to the axis of the cylinder of which recess 13 forms a part. The slot 28 is made long enough to permit adjustment of the slide member 14 from the end position shown in Fig. 1 upwardly to an opposite end position where the axis of rotation of drum 17 makes an angle with the axis of rotation of rotary head 4 of the same size as the angle shown in Fig. l.

The cylinder drum 17 is formed with bores 29 respec tively communicating with the cylinder bores 16 and with the end face of the cylinder drum located distant from the rotary head and slidably engaging the right planar face portion of slide member 14, as viewed in Fig. l, the axes of bores 29 being elements of a cone whose apex is located in the axis of rotation of the cylinder drum 17. Furthermore, the left end face of the cylinder drum 17, as viewed in Fig. l, is formed with a plurality of arcuate recesses 31 (see also Fig. 4) which respectively communicate with the interior of cylinder bores 16 through the bores 30. Between the recesses 31 and the bores 29, the left end face of the cylinder drum 17, as viewed in Fig. l, is formed with an annular depression 32 (see also Fig. 4).

Fig. 2 shows a half of the cover 12 as seen from the interior of the pump, and the right cylindrical outline of recess 13 is evident from Fig. 2. The bore 26 for the adjusting rod 27 is shown in dotted lines in Fig. 2, and Fig. 2 also shows one half of the slot 28 through which the pin 24 extends. As is evident from Fig. 2 an opening 33, shown in dotted lines in Fig. 1, extends through the cover 12 and studs 34 fixed to the outer face of the cover 12 on opposite sides of opening 33 are adapted to connect a pipe or the like to the cover for leading fluid to or from the pump and the opening 33. A similar opening 33 and studs 34 are provided on the other half of the cover which is not shown in Fig. 2, the cover being symmetrical so that the left half thereof which is not shown in Fig. 2 is identical with the right half thereof shown in Fig. 2. Also, Fig. 2 shows four of the bores 35 through which screws extend for fixing the cover 12 to the housing 1. As is evident from Fig. 2, each side of the cover 12 is formed with a threaded bore through which an outwardly threaded adjusting screw 36 threadedly extends, this screw 36 having at its inner end an eceentrically located bearing pin portion 37 on which a roller 38 is turnably mounted. Each screw 36 is fixed in its adjusted position through the medium of a lock nut 39 threadedly engaging the screw 36 and located in a countersunk recess formed in the cover 12 at each side thereof.

Fig. 3 shows a section of the slide member 14 through an elongated groove 40 of the slide member 14, this groove 40 communicating at a central portion thereof with an arcuate depression 41 formed in the right planar face of slide member 14, as viewed in Fig. 3. Two such grooves 40 and arcuate depressions 41, which form a part of a circle, are formed in the slide member 14 and are symmetrically l0cat"d with respect to the axis of pin 15.

Further details of the construction are shown in Figs. 4-6. Fig. 4 shows the left half of the slide member 14 as seen from the housing cover 12, and it is evident from Fig. 4 that each of the grooves 40 are quite narrow and of considerable length. The outline of the depression 41 which communicates with groove 40 is shown in Fig. 4. Also, Fig. 4 shows the end face of cylinder drum 17 which is distant from the rotary-head 4, the portions of this end face which slidably engage the slide member 14 during rotation of the .cylinder drum being shaded in Fig. 4 while the recesses 31 which communicate with the cylinder bores through the bores 30, respectively, and the annular depression 32 as well as the oval ends of bores 29 are shown in the unshaded portions of Fig. 4.

The convex face of slide member 14 (Figs. 9 and 10) is provided between and at the outer sides of grooves 40 with flattened portions 44 located centrally of the slide member 14 and distributed laterally across the same, and the convex face of slide member 14 is also formed with the intersecting grooves 42 and 43 which are located closely adjacent to the grooves 40 so that the latter are surrounded with a very narrow sealing surface portion which slidably engages the mating concave surface portion at recess 13 of cover 12. In order to better illustrate grooves 42 and 43 and flattened portions 44 of slide members 14, all other parts of Fig. 4 are shaded.

Fig. 5 shows the slide member 14 as seen from the side thereof, and Fig. 5 clearly illustrates one of the arcuate slide flanges 45 of slide member 14. Also, Fig. 5 shows a flattened portion 44 and grooves 43 of the slide member 14.

Fig. 6 shows the housing 12 with the slide member 14 located therein, the pin 15 fixed to the slide member 14 also being shown in Fig. 6, and the cooperation between engaging the flanges 45 to maintain the convex face of slide member 14 in engagement with the concave face of recess 13.

Fig. 6 also shows a pair of bores 47 extending through the slide member 14 and communicating with depression 32 of cylinder drum 17 (Fig. 4) as well as with the outer flattened portions 44 of the slide member 14 so that any oil or other fluid which leaks into the depression 32 will not build up a pressure but will instead be directed by the bores 47 to the grooves 42 and 43 and to the interior of the pump housing.

Also, Fig. 6 shows the pair of openings 33 of the cover 12 as well as a part of the grooves 40 of slide member 14 which communicate respectively with the openings 33 and which also respectively communicate with the arcuate depressions 41 of slide member 14. It

will be noted particularly from Fig. 4 that the depressions 41 are located along the circular path through which the ends of bores 29, at the face of drum 17 which slidably engages member 14, turn so that these bores 29 communicate with openings 33 through the arcuate depressions 41 and the grooves 40 of the slide member 14.

Fig. 7 shows one half of the apertured plate 7 and indicates how many apertures are provided in the plate 7. As was mentioned above, the ball members 6, which respectively transmit the axial thrust of the rotary head 4 to the pump housing, are respectively located in the apertures of the plate 7.

Fig. 8 shows on an enlarged scale and partly in section one of the piston rods 19 as well as the structure for connecting each piston rod 19 to a piston 18, on the one hand, and to the rotary head 4, on the other hand. Thus, the end portion 48 of piston rod 19 is threaded and is threadedly fixed to piston 18 by engaging the threaded surface of an axial bore formed in the right end of piston 18, as viewed in Fig. 1. The piston rod 19 is provided adjacent its right end, as viewed in Fig. 8, with an annular integral flange 49 which slidably engages at its opposite faces a pair of rings 50, respectively, which are provided with convex annular outer faces forming a part of a sphere of the same magnitude as the sphere of which the recess 20, into which piston rod 19 extends, forms a part so that the rings 50 slidably engage the rotary head at each recess 20 thereof with substantially no play. The flange 49 is formed :at side thereof distant from the piston with an annular recess 51 so that only a small area of this side face of flange 49 slidablyengages the right ring 50, as viewed in Fig. 8. As is evident fromFig. 8, the inner diameters of rings 50 are substantially larger than the cylindrical cross section of that portion of piston rod'19 which extends through rings 50. The Opposite planar faces of flange 49 are in slidable engagement with the planar faces of rings 50 which confront each other, respectively, so that the piston rod 19 is capable of sliding laterally with respect to the rings 50. The latter rings serve to connect the piston rods to the rotary head with the necessary universal movement of the piston rods with respect to the rotary head. Each piston rod 19 is formed with an axial bore 52 which communicates with the interior of one of the cylinder bores 16 and which also communicates through the'recess .20 with th e annular depression 51 of flange 49 so that the interior of recesses 20 as Well as depressions 51 always contain fluid at the same pressure as the fluid in the interiorof the cylinder bores 16.

The manner in which the above-described structure operates to pump a fluid is believed to .be self-evident. The unillustrated drive shaft rotates the rotary head 4 which transmits its rotation to the cylinder drum 17 through the pistons 18 and piston rods 19. When the rod 27 is raised from the position shown in Fig. 1 tot! position where the axis of rotation ofdrum -17 coincides with the axis of rotation of rotary head 4, the pistons 18 will not reciprocate in the cylinder bores 16 and there will be no pumping action. If rod 27 is actuated to move the slide member 14 and cylinder drum 17 therewith toward the position shown in Fig. 1, then the pistons 18 will be drawn outwardly of the cylinder bores during one half of a rotation and will be pushed into the cylinder bores during the other half of a rotation so that in this way fluid will be sucked into the cylinder bores through one of the openings 33 of the cover and will be. forced out of the pump through the other of the openings 33. The direction of fluid flow may be reversed by moving the slide member 14 and cylinder drum 17 upwardly instead of downwardly from their horizontal position, as viewed in Fig. l, and the stroke of the pistons is regulated by the extent 'to which the cylinder drum is moved from the position where its axis of rotation coincides with the axis of rotation of the rotary head.

It should be noted that the grooves 40 are long enough to fully cover the openings 33 in all positions of the slide member 14, as is evident from the dotted lines in Fig. 1. mitted directly through slide member 14 to the cover 12 so that the pump can Withstand high fluid pressures and will operate quietly. It will be noted that the length of slide member 14 is not much greater than the diameter of the cylinder drum 17, so that the size of the pump of the invention is quite small, and the shortness of the length of slide member 14 enables the entire pump housing to be reduced in size, as compared to known rotary piston pumps. The arrangement of grooves 4i) and arcuate depressions 41 enables quite a large amount of fluid to be transferred quickly along an extremely short path through the slide member so that the efiicienc'y of the pump is increased in this way and full suction of the pumped fluid is obtained even at high speedsof rotation of the cylinder drum, The seal between the cylinder drum and slide member is maintained even;

when the pump is operated at high capacity becauserthe. I

to the rod 27. The force with which the slide member The axial thrust of the cylinder drum is trans- 14 frictionally bears against the concave curved face of cover 12 works against easy movement of adjusting rod 27. However, this latter force of friction is greatly reduced according to the invention by the large cross sectional area of the base surfaces of grooves 40 which face the cover 12 and by the arrangement of flattened portions 44 and grooves 42 and 43 of the slide member 14 which provide about the grooves 40 an extremely narrow sealing surface which slidably bears against the concave inner surface of the cover. Thus, the thrust of the slide member toward the cover is transmitted in large part hydraulically by the grooves 40, and the actual contact between the slide member and cover is greatly reduced by the flattened portions 44 and the grooves 42 and 43 of the slide member. The pressure of the fluid in grooves 40 is never great enough to move slide member 14 away from cover 12, the total area of the bases of grooves 40 being almost but not as great as the cross section of that part of the cylinder drum which is under pressure. In this connection it should be noted that the location of the flattened portions 44 at the central part of slide member 14 guarantees a seal between the cover and slide member even after the surface portions of the slide member which surround the grooves 40 at the convex face of the slide member become worn. The guide rollers 38 are adjusted to guarantee sealing engagement between the cover and slide member 14 even when the pump operates without a fluid pressure load. The adjusting rod 27 may be operated either mechanically, hydraulically or electrically. i

The location of bores 29 along a cone locates the ends of these bores at slide member 14 along a circle which is of a much smaller diameter than the outer d'amzter of the cylinder drum. In this way the linear speed of the ends of bores 29 at slide member 14 is maintained at a relatively small value even when the cylinder drum rotates at a high speed so that there is a very small loss of hydraulic fluid even when the pump is operating at high speed. This arrangement, however, requires the cylinder drum to be formed at its end face which engages the slide member 14 with the recesses 32 in order to prevent unbalanced forces and bending moments from arising. In order that there be no undesirable bend ng moments, it is necessary that those cylinders of the cylinder drum which at a given instant communicate with the discharge arcuate depression 41 have pressure forces whose resultant is located at the center of the cross section of the arcuate depression 41 through which the pressure fluid is discharged, so that no bending moments are produced and so that a good surface contact between the cylinder drum and slide member 14 is assured. The bores 29 which are directed from the cylinder bores 16 toward the axis of rotation of the cylinder drum work against this result and would give rise to unbzlanced forces and bending moments were it not for the recesses 31. The location of the bores 29 nearer to the axis of the cylinder drum than the cylinder bores themselves necessitates location of the arcuate depressions 41 along a circle which is smaller than the circle along which the cylinder bores are distributed so that without the recesses 31 an unbalanced force and bending moment would be produced. These recesses 31 counterbalance the bending moments and unbalanced forces which tend to be produced by the location of annular depressions 41, because of the location of the recesses 31 along a circle of greater diameter than that along which the cylinder bores 16 are distributed, and in fact the recesses 31 are located as close as possible to the periphery of the end face of the cylinder drum shown in Fig. 4. Because the recesses 31 are provided with pressure fluid through the bores 30 they counteract any unbalance which tends to be produced by the location of annular depressions 41 with respect to the cylinder bores, and in this way it is possible with the structure of the invention to provide a quietly operating balanced pump which still possesses the advantage of moving the ends of bores 29 'at slide member 14 at a relatively low linear speed even though the cylinder drum is rotating at a high speed. a It will be noted that the annular depression 32 greatly cuts down the area of the surface portion of drum'17 which surrounds recesses 31 and the ends of bores 29 so that the desired seal between the cylinder drum17 and slide member 14 is maintained with a minimum of friction. No pressure can build up between slide member 14 and cylinder drum 17 because any fluid which gathers in depression 32 flows through bores 47 and through the spaces defined by the cylinder cover and flattened portions 44 of slide member 14 along grooves 43 and 42 and to the interior of the pump housing.

The piston rods 19 provide a very simple and inexpensive means for transmitting the rotation of the rotary head 4 to the cylinder drum 17. The fixing of the piston rods to the pistons is extremely simple, and the rings 50 provide the necessary universal movements of the piston rods with respect to the rotary head. The piston rods are free to move laterally by the s'iding engagement of their flanges 49 with the pairs of rings 50 engaging the same, and the drive from the rotary head is in fact obtained by such sliding of the flanges 49, since, during driving of the cylinder drum by the rotary head each pair of rings 50 engages at its inner cylindrical bores the cylindrical outer surface of piston rod 19 along a line of contact. The hydraulic connection of the interior of recesses 20 and annular recesses 51 with the interior of the cylinder bores 16 greatly reduces losses resulting from friction in the structure which connects the piston rcds to the swashplate. It should be noted that the largest diameter of each annular recess 51 is the same as or smaller than the diameter of a piston 18. Through this expedient the piston pressure is transmitted to the rotary head in large part hydraulically.

The hardened ball members 6 efliciently distribute the thrust of the rotary head 4 over a large area and the flange 8 of the rotary head cooperates with the rollers of roller bearing 3 to provide an efficient rotatable mounting for the rotary head, the flange 8 cooperating with the rollers of roller bearing 3 and the rotary head itself cooperating with ball members 6 to prevent axial shifting of the rotary head. It should be noted that the drive shaft is not rigidly connected to the rotary head and instead has the splines thereof in a somewhat loose mating engagement with the splines 9 of the rotary head so that some small degree of universal movement of the rotary head and drive shaft with respect to each other is possible, and in this way the drive shaft cannot disturb the engagement between the rotary head and the ball members 6, on the one hand, and the rollers of roller hearing 3, on the other hand.

The above described rotary piston pump transmits the thrusts directly to the pump housing and assures a noiseless operation of the pump even at high pump pressures. The simple manner in which the pump fluid is paced in communication with the interior of the cylinder bores through passages defined in part by sealing surfaces which maintain their sealing engagement even after a long period of time and in part through arcuate depressions 41 of small diameter provides a high hydraulic efl'iciency and a low heating of the pump fluid. The short length and large cross section of the passages for the pumped fluid guarantees proper suction even at high speeds of rotation of the cylinder drum and even when it is located at either of its end positions.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of pumps differing from the types described above.

While the invention has been illustrated and described as embodied in rotary piston pumps, it is not intended to be limited to the details shown, since various modifications and structural changes may be made'witho ut 9 departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a rotary piston pump, in combination, a hollow housing having a cover provided at its inner face with a curved concave surface forming part of a cylinder, said cover being formed with inlet and outlet openings extending from said curved surface through said cover; a cylinder drum formed with a plurality of cylinder bores and with cylinder passages respectively extending from said cylinder bores to an end face of said cylinder drum; a slide member having a first convex face of the same curvature as said concave surface of said cover in rotatably slidable engagement with the latter, the. circumferential length of said convex face being substantially shorter than the circumferential length of .said concave surface, said slide member having an opposite second face in slidable engagement with said end face of said cylinder drum and covering the ends of said cylinder passages at said end face of said drum, said drum being rotatable about an axis perpendicular to said second face of said slide member, said slide member being formed with a pair of slide member passages respectively communicating at said first face of said slide member directly with said inlet and outlet openings of said cover and respectively terminating at said second face of said slide member on opposite sides of the axis of said cylinder drum and along the path through which said ends of said cylinder passages move during rotation of said drum; means cooperating with said drum for rotating the latter; and adjusting means operatively connected to said slide member for adjusting the position thereof along said concave surface of said cover so as to thereby adjust the inclination of the axis of said cylinder drum, said slide member passages respectively communicating with said openings in all positions of said slide member.

2. In a rotary piston pump, in combination, a hollow housing having a cover provided at its inner face with a curved concave surface forming part of a cylinder, said cover being formed with inlet and outlet openings extending from said curved surface through said cover; a cylinder drum formed with a plurality of cylinder bores and with cylinder passages respectively extending from said cylinder bores to a planar end face of said cylinder drum; a slide member having a first convex face of the same curvature as said concave surface of -said cover in rotatably slidable engagement with the latter, the circumferential length of said convex face being substantially shorter than the circumferential length of said concave surface, said slide member having an opposite, planar second face in slidable engagement with said planar end face of said cylinder drum and covering the ends of said cylinder passages at said end face of said drum, said drum being rotatable about an axis perpendicular to said second face of said slide member, said slide member being formed with a pair of slide member passages respectively communicating at said first face of said slide member directly with said inlet and outlet openings of said cover and respectively having at said second face of said slide member arcuate ends forming part of a circle, and being located on opposite sides of the axis of said cylinder drum along the path through which said ends of said cylinder passages move during rotation of said drum; means cooperating with said drum for rotating the latter; and adjusting means operatively 1'9 connected to said slide. member. for adjusting the po'sie' tion thereof along said concave surface of said cover so as to thereby adjust the inclination of the axis of said cylinder drum, said slide member passages having: at said first face of said slide member a length greater than said openings, respectively.

3. In a rotary piston pump, in combination, a hollow housing having a cover provided at its inner face with a curved concave surface forming part of a cylinder, said cover being formed with inlet and outlet openings extending from said curved surface through said cover; a slide member adapted to rotatably carry a cylinder drum and having a convex face of the same curvature as said concave surface of said cover in rotatably slidable engagement with the latter, the circumferential length of said convex face being substantially shorter than the circumferential length of said concave surface, saidslide member being formed with a pair of passages passing through said slide member and having at said convex face of said slide member elongated ends respectively communicating with said openings of said cover in all positions of said slide member along said cover; and member for adjusting the position thereof along said concave surface of said cover.

4. In a rotary piston pump, in combination, a hollow housing having a cover provided at its inner face with a curved concave surface forming part of a cylinder; a slide member having a convex face of the same curvature as said concave surface of said cover in rotatably slidable engagement with the latter, the circumferential length of said convex face being substantially shorter than the circumferential length of said concave surface, said slide member having an elongated projection extending from each of its side faces; a pair of rollers respectively engaging said projections at faces thereof directed away from said cover; and a pair of adjusting screws threadedly carried by said housing and respectively having eccentric inner end portions on which said rollers are turnably mounted so that by turning said screws said rollers may be adjusted to maintain said convex face of said slide member in engagement with said concave surface of said cover.

5. In a rotary piston pump, in combination, a hollow housing having a cover provided at its inner face with a curved concave surface forming part of a cylinder, said cover being formed with inlet and outlet openings extending from said curved surface through said cover; a cylinder drum formed with a plurality of cylinder bores distributed along a first circle extending about the axis of said drum, said cylinder drum being formed with cylinder passages respectively extending from said cylinder bores to an end face of said cylinder drum and terminating at said end face of said drum along a second circle of a smaller diameter than said first circle, said end face of said cylinder drum being formed with a plurality of recesses respectively communicating with said cylinder bores and located along a third circle of a larger diameter than said first circle; a slide member having a first convex face of the same curvature as said concave surface of said cover in rotatably slidable engagement with the latter, the circumferential length of said convex face being substantially shorter than the circumferential length of said concave surface, said slide member having an opposite second face in slidable engagement with said end face of said cylinder drum and covering the ends of said cylinder passages and said recesses at said end face of said drum, said drum being rotatable about an axis perpendicular to said second face of said slide member said slide member being formed with a pair of slide member passages respectively communicating at said first face of said slide member directly with said inlet and outletso penings of said cover and respectively terminating at said second face of said slide member on opposite sides of the axis of rotation of said cylinder drum and along the path through which said ends of said cylinder passages '11 move during rotation of said drum; means cooperating with said drum for rotating the latter; and adjusting means operatively connected to said slide member for adjusting the position thereof along said concave surface of said cover so as to thereby adjust the inclination of the axis of said cylinder drum.

6. In a rotary piston pump, in combination, a hollow housing having a cover provided at its inner face with a curved concave surface forming part of a cylinder, said cover being formed with inlet and outlet openings extending from said curved surface through said cover; a cylinder drum formed with a plurality of cylinder bores distributed along a first circle extending about the axis of said drum, said cylinder drum being formed with cylinder passages respectively extending from said cylinder bores to an end face of said cylinder drum and terminating at said end face of said drum along a second circle of a smaller diameter than said first circle, said end face of said cylinder drum being formed with a plurality of recesses respectively communicating with said cylinder bores and located along a third circle of a larger diameter than said first circle, said end face of said cylinder drum being formed with a depression located closely adjacent to said recesses so that the latter are surrounded with only a. relatively small surface portion of said end face of said drum; a slide member having a first convex face of the same curvature as said concave surface of said cover in rotatably slidable engagement with the latter, the circumferential length of said convex face being substantially shorter than the circumferential length of said concave surface, said slide member having an opposite second face in slid:.ble engagement with said end face of said cylinder drum and covering the ends of said cylinder passages and said recesses at said end face of said drum, said drum being rotatable about an axis perpendicular to said second face of said slide member, said slide member being formed with a pair of slide member passages respectively communicating at said first face of said slide member with said inlet and outlet openings of said cover and respectively terminating at said second face of said slide member on opposite sides of the axis of said cylinder drum and along the path through which said ends of said cylinder passages move during rotation of said drum so that said cylinder passages successively communicate with said slide member passages during rotation of said drum, said slide member being formed with at least one bore passing therethrough from said first to said second face thereof and communicating With said depression in said end face of said drum so that oil which gathers in said depression may flow through said slide member to the interior of said housing; means cooperating with said drum for rotating the latter; and adjusting means operatively connected to said slide member for adjusting the position thereof along said concave surface of said cover.

7. In a rotary piston pump, in combination, a hollow housing; rotary head means rotatably mounted in said housing and formed with recesses distributed about the axis of rotation of said rotary head means and each forming part of a sphere; a pair of substantially identical rings spaced from each other, located in each recess of said rotary head means and each having an outer surface forming a part of a sphere of the same magnitude as the sphereof which said recess forms a part so that said rings are slidable without play in said recess; a piston rod extending into each recess through said pair of rings therein and having in the region of said rings a cylindrical cross-section substantially smaller than the inner diameter of said rings and said piston rod having an annular flange located between and slidably engaging said rings at opposite faces of said flange, respectively, said piston rod being bored through its entire length, and said fiange being formed in a face thereof with an annular groove; a plurality of pistons each of which has a diameter substantially equal to the outer diameter of said annular groove, said pistons being respectively fixed to said piston rods at portions thereof spaced from said rotary head means; and a cylinder drum formed with a plurality of cylinder bores into which said pistons slidably extend, re spectively, so that said rotary head means, when driven, transmits rotation to said cylinder drum through said piston rods, the latter engaging said rings along a line of contact, and so that said pistons reciprocate in said cylinder bores during rotation of said cylinder drum and rotary head means when the axes of rotation of said cylinder drum and rotary head means are out of coincidence with each other, said cylinder bores respectively communicating with the bores of said piston rods.

8. In a rotary piston pump, in combination, a housing; rotary head means rotatably mounted in said housing and formed with a plurality of recesses distributed about the axis of rotation of said rotary head means and each forming part of a sphere; a plurality of piston rods extending respectively into said recesses and respectively having annular flanges respectively loacted in said recesses; and

a pair of substantially identical rings located in each recess and slidably engaging opposite faces, respectively, of the annular flange located in said recess, each of said piston rods extending through central openings of said pair of rings, said rings each having an inner diameter larger than the cross section of the piston rod extending through the same and each having an outer convexly curved annular face of the same curvature as the recess in which said rings are located, so that said rings are slidably supported by said rotary head means without play.

References Cited in the file of this patent UNITED STATES PATENTS Re. 20,026 Thoma June 30, 1936 1,137,283 Pratt Apr. 27, 1915 1,659,374 Robson Feb. 14, 1928 1,794,946 Crain Mar. 3, 1931 2,081,477 Egersdorfer May 25, 1937 2,303,955 Rose Dec. 1, 1942 2,313,407 Vickers Mar. 9, 1943 2,445,232 Molly July 13, 1948 2,604,856 Henrichsen July 29, 1952 2,633,104 Lauck Mar. 31, 1953 2,649,741 Henrichsen Aug. 25, 1953 2,674,196 Ferris Apr. 6, 1954 FOREIGN PATENTS 580,593 Great Britain Sept. 12, 1946 597,476 Germany Dec. 18, 1929 633,619 Great Britain Dec. 19, 1949 

